C.1.5 Virtual-Display Device Services and Notifications

The virtual display device for 386 enhanced-mode Windows also provides Interrupt 2Fh service and notification functions. Windows display drivers use these functions to check for and manage screen switching. There are the following functions:

Enable VM-Assisted Save/Restore (Interrupt 2Fh Function 4000h)

Notify Background Switch (Interrupt 2Fh Function 4001h)

Notify Foreground Switch (Interrupt 2Fh Function 4002h)

Enter Critical Section (Interrupt 2Fh Function 4003h)

Exit Critical Section (Interrupt 2Fh Function 4004h)

Save Video Register State (Interrupt 2Fh Function 4005h)

Restore Video Register State (Interrupt 2Fh Function 4006h)

Disable VM-Assisted Save/Restore (Interrupt 2Fh Function 4007h)

For more information about using these functions, see Chapter 2, “Display Drivers.”